Ukraine, Russian forces opening fire this weekend. Completing a takeover of territory Russia now claims is its own. Alex Marquardt and his team have been in the middle of it all. And he joins us now with the latest. Alex. Reporter: Good morning, Martha. This says it all, the parliament in crimea's capital waving a huge Russian flag. The mysterious Russian forces in crimea over the last few weeks, no longer hiding their identity. Proudly showing off they and now crimea are Russian. It was one of the last major bases in Ukrainian control, and the Russians wanted it. Firing warning shots and sound grenades, special forces on Saturday fanned out across the base. This is a very tense standoff between the Russian special forces, the Ukrainian soldiers who turned their backs on the Russians. Refusing to surrender. They may soon not have a choice. Realizing the base was gone, the colonel gave an emotional thanks to his men. ? who responded with the national anthem. Crimea is now Russia. Ukrainian symbols erased, the Russian flag raised. The United States and Europe have refused to recognize Russia's takeover, imposing the toughest sanctions on Russia since the cold war and threatening more. The latest white house targets, 20 officials. Including several in president poo Putin's innermost circle. And Russia had sanctions on nine white house officials and members of congress. Putin says that's it, but left the door open for more. As some 20,000 troops mass near the border with eastern Ukraine. Fueling fears at the white house that is Putin's next move. Jonathan Karl is with president Obama as he watches closely. Reporter: Good morning. I'm here at anders air force base. Soon heading out to Europe with president Obama. It's sure to be dominated by the crisis in Ukraine. They are meeting with the europeans and the group of seven industrialized nations to talk about what further steps they can take to put pressure on Russia. There's real concerns about what Putin will do next. Privately, white house officials will acknowledge there's virtually no hope of getting Russia to withdraw from crimea. This is about getting Putin from going any further. And the big picture here, there has been a fundamental change in u.s./russian relations. Now at the worst point since the cold war and unlikely to improve any time soon, Martha.

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